There are many different types of roof flashings used to seal openings around pipes extending through the roofs of buildings that have met with varying degrees of success. Many roof flashings include elastomeric collars to form the seal around the pipes. However, roof flashings with elastomeric collars are not recommended for use in tarred roof environments because the tar attacks the elastomeric material and may cause premature leakage.
Accordingly, lead roof flashings are most commonly used to seal pipes protruding from tarred roofs. However, the lead flashings are a potential health hazard because of possible contamination to the run-off water which comes into contact with the lead. Also, lead flashings are relatively expensive and much more bulky than most other flashings, and are more susceptible to damage, making them more difficult and costly to ship and install.